The invention relates to a driving-in tool, comprising a driving-in piston, guided in a cylinder, for driving a nail element into a workpiece, and a combustion chamber which is arranged at the driving-in piston and can be filled with an ignitable fuel-gas mixture. A positive pressure of the fuel-gas mixture in the combustion chamber can be produced by a movement of the driving-in piston. At least one of the two, the combustion chamber or the cylinder, is connected to an external space via a valve member, the positive pressure of the fuel-gas mixture produced by the driving-in piston being selectively adjustable by means of the valve member.